Recently, as disclosed in Patent Literature 1 (JP 2000-171320A) for example, it has been proposed that a piezoelectric pump (a pump that drives a diaphragm using a piezoelectric element) is used as a pump for sending fluid to a blood pressure measurement cuff (refers more accurately to an air bladder contained in a cuff. The same follows below.) of a blood pressure meter.
For example, as disclosed in Patent Literature 2 (JP 2010-142783A), as a publicly-known driving circuit for driving a piezoelectric pump, there is known to be a method of stepping up a low-voltage power supply so as to generate a high-voltage driving power supply for a piezoelectric element, amplifying the low-voltage driving waveform using an amplifier while using the driving power supply, and obtaining a driving signal for driving the piezoelectric element. Also, as disclosed in Patent Literature 3 (JP 2009-50051A), there is known to be a method in which the power supply voltage is switched (according to the driving frequency for the piezoelectric element) on the primary side of a transformer, and the driving voltage is applied to the piezoelectric element that is connected to the secondary side of the transformer.